In a little under two weeks the launch window for NASA's Double Asteroid Redirection Test (DART) mission opens.
In a world, maybe even universe first, plan the space agency will slam a spacecraft into the non-hazardous moonlet asteroid Dimorphos, which is about 160 metres in diameter.
The goal is to see whether it's possible to knock the space rock off its orbit.
Planetary scientist at the University of Queensland Trevor Ireland told 9news.com.au this is one of two methods humanity has to stop a potentially hazardous object (PHO) from slamming into Earth.
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The other option would be to use a nuclear blast to blow the asteroid apart, Professor Ireland explained.
"What we've discovered over the last couple of years is a lot of the near-Earth asteroids are potentially rubble piles," he said.
"So if you put a lot of energy into them, they are just going to fly apart.
"They are not well held together."
Professor Ireland said this then prompts the question: "Do you let it come in as a bullet or as shotgun scatter?"
"You don't want it blowing up too close to Earth as that generates debris," he said.
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Professor Ireland said he believes deflection, through the DART method, is humanity's best option to defend Earth.
If time and proximity is not an issue, Professor Ireland said placing a sail on an asteroid could also potentially change it's orbit.
"You could attach a parachute effectively to the asteroid, and I say attach rather glibly, that sail could produce solar wind to push and pull on it a bit," he explained.
"But most of these methods, beyond hitting [a potentially hazardous object] with something to try and bash it out of the way, require force over a long period of time."
Is Earth currently at risk from a potentially hazardous object?
Kelly Fast is a planetary defence expert and a manager in NASA's Planetary Defence Coordination Office.
She with certainty an asteroid would hit our planet again.
"Asteroids have hit Earth over the course of its history, and it will happen again," Dr Fast said on the space agency's website.
"Dust, meteoroids, and even small asteroids hit Earth all the time.
"But impacts of asteroids that affect the surface are much rarer and happen on time scales of hundreds to thousands to millions of years."
Professor Ireland said the asteroid Bennu poses the greatest risk to Earth.
The space rock is about 492 metres in diameter.
The good news is, it won't pose a risk for more than 100 years.
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Should it hit though, studies show it would create a crater between 10 to 20 times its size - and cause an area of devastation that could reach 100 times the size of the crater.
Professor Ireland said civilisation-ending asteroids are much rarer and would have to measure more than a kilometre in diameter, at least, to be "extinction-level".
For reference, the Chicxulub impactor that wiped out the dinosaurs was about 9.6 kilometres.
NASA estimates about 40 per cent of asteroids larger than 140 metres have been found to date.
But this is no cause for alarm.
The better news is these large asteroids are easier for astronomers to find, meaning it's unlikely one should suddenly "pop up" and pose a risk.
"There's about a million one kilometre asteroids in the asteroid belt," Professor Ireland said.
"The likelihood of one of those suddenly meandering down to Earth is very remote."
Contact Raffaella at rciccarelli@nine.com.au.
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